In digging work in a mine, a technique to use an unmanned vehicle capable of traveling autonomously for the purpose of enhanced safety and cost reduction is demanded. As for digging work, in the case of so-called open-pit mining in which digging is done from the earth's surface into the underground in a swirling manner without making a drift to mine minerals near the earth's surface, it is necessary to excavate gravel in the deepest area and transport the excavated gravel to outside the mining site. For transportation of the gravel to outside the mining site, a huge dump truck with a large load capacity or the like is used; however, the amount of transported gravel per unit time is directly related to the progress of mining and thus the gravel must be transported by a dump truck traveling at high speed.
On the other hand, in order to transport a large amount of gravel to outside the mining site efficiently, a plurality of dump trucks must travel outward and homeward many times on a road for transportation and it is important to take countermeasures against collision between dump trucks traveling outward and homeward and tumbling of dump trucks from cliffs.
The related art which reduces collisions during high speed traveling of dump trucks is disclosed in Patent Literature 1. In the travel control apparatus for vehicles disclosed in Patent Literature 1, when another vehicle is absent near the subject vehicle, the subject vehicle is made to travel on a solo traveling course set around the center of the road. Only when the vehicles come closer and should pass by each other, the subject vehicle is made to move to a passing-by course located near a road side at lower speed and allows the other vehicle to travel past and then increases the speed to travel at high speed again while moving back to the solo traveling course.
In Patent Literature 1, when the road width is considered in traveling, the road width and the vehicle position on the road are calculated from course data stored in a course data memory unit and the vehicle position measured by a vehicle position measuring unit such as a GPS.